Hepatitis C - Diagnosis
What kinds of tests did you have to diagnose your hepatitis C?
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What are the diagnostic tests for hepatitis C virus and how are they used to diagnose hepatitis C infection?
Several diagnostic tests currently are available for the diagnosis of HCV infection. They can be categorized according to the way the tests are used.
Screening tests
Screening tests are tests that are used to diagnose a condition or disease among individuals not known to have the disease. They are is particularly useful for individuals who have risk factors for the condition or disease.
The first step in screening for HCV infection is to test blood for the antibody to HCV using an enzyme immuno-assays (EIAs). If the EIA test is negative (does not find the antibody), the patient is assumed to be free of HCV. It takes several weeks (up to six months) for antibodies to develop after the initial infection with HCV, so this screening test may miss a few newly-infected individuals. The EIA screening tests are very good (specific); if the test is positive the probability of having HCV infection is greater than 99%.
Recombinant immunoblot assay (RIBA) is used to confirm the positive results of EIAs since occasionally a positive EIA is a false positive, that is, the test is positive when HCV is not present. Although the direct detection of HCV RNA (HCV PCR) also is widely used to confirm the HCV infection, RIBA is still useful to differentiate false positive results in the few individuals whose immune systems have eliminated the virus but still have antibodies left over from the resolved infection.
As previously described, HCV contains RNA. Several tests (assays) are available to measure the amount of HCV RNA in a person's blood. These tests are referred to as molecular tests because they examine the virus at the molecular level. A single negative test for RNA does not mean that there is no infection because the virus may appear in the blood intermittently or may exist in small amounts. Newer tests have helped by detecting smaller and smaller amounts of virus in the blood.
Testing for RNA is useful in determining whether or not a patient has circulating virus in the blood (viremia). Hence, it can be used to confirm that a positive EIA/ELISA truly reflects active HCV infection.
RNA testing also should be done in individuals who may have been recently exposed to HCV. HCV RNA testing is more sensitive (that is, will detect more cases) than the conventional EIA testing in this setting. The reason for this greater sensitivity is that it may take a person several weeks after exposure to HCV to develop the antibodies, whereas HCV RNA becomes detectable one to three weeks after exposure. Finally, HCV RNA testing may be helpful to assess a patient's response to treatment at certain time points during antiviral therapy (see treatment of HCV below).
Blood tests also have been developed to identify the HCV genotype. This information is used to help guide treatment.
The table below provides guidelines for interpreting the results of testing for HCV antibodies by EIA and RIBA and for hepatitis C virus RNA. These are standard interpretations, but it is important to remember that the diagnosis of HCV infection should be made by an experienced clinician who is familiar with the patient's medical history.
| Anti-HCV (ELISA/EIA) | Anti-HCV (RIBA) | HCV RNA | Interpretation |
| Negative | Negative | Negative | No infection |
| Positive | Positive | Positive | Ongoing infection |
| Positive | Positive | Negative | Past or current infection. Additional or repeat testing should be done to exclude fluctuating or low levels of viremia. |
| Positive | Negative | Negative | False positive ELISA; no infection |
| Positive | Indeterminate | Negative | Situation unclear, consider additional testing |
| Negative | Negative | Positive | New (acute) HCV infection or chronic HCV infection in an immunocompromised person unable to make adequate antibodies. |
See what others are saying
I was diagnosed with hepatitis C in September of 2008. I went in for a routine physical. I asked for the blood test, as my family has a history of diabetes/heart problems. My doctor performed a biopsy at the end of December and determined I was at the end of stage 0/beginning of stage 1. I just had blood work done this month. My AST is 45 and ALT is 78. Everything else is within limits. My wife and I are searching, debating, and researching when/how my course of treatment should go. So as of now, treatment is on hold.
I have had hepatitis C since 1976. When I got it, I was very ill. I lost 20 pounds in two months, and I was told that I had a form of hepatitis that was not A or B. (They didn't have a name for it, so they would call it B.) In 1996, after they discovered C, I had my family doctor test me for it, and it was confirmed as hepatitis C. I was 22 when I got it. I am now 54 and have had a pretty healthy life so far, with only a few complications from my disease. I am frightened to take the interferon/ribovarin treatment because of the side effects, and also because I have genotype 1A known not to respond well to treatment, especially after 34 years with the virus. I had a biopsy a month ago, I was found to be free of cirrhosis and cancer, although I do have some scarring due to inflammation. I've been taking herbals for three years, selenium, milk thistle, omega 3, licorice root, esther c, and generally feel well with a good energy level. My white blood cell count is excellent, my viral load is two million, and my platelets are good. I seem to be in good health other than the hepatitis C. I don't drink or do things to damage my health, and I eat nutritious foods known to be good for your liver and digestive system. You can live a long time with this disease and remain active and healthy if you just use common sense and self-discipline. I'm hoping to make it into my 70s. Oh, and people think I'm only in my 40s when they meet me.
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